Nightmare disorder

What is nightmare disorder?

Nightmares can be defined as vivid and terrifying dreams which awaken the dreamer from sleep. Typically, the dreamer wakes from the rapid eye movement (REM) stage of sleep and can remember a detailed, perhaps bizarre dream plot. There is evidence that frequent nightmares are associated with insomnia and poor-quality sleep.¹

Although such dreams are part of normal human experience, for some they can be a recurrent and extremely troubling problem. This is particularly so for young children, but they can be disruptive to the whole family. Explanation and reassurance are often helpful particularly for parents who can then in turn be more reassuring to the affected child.

It is important to distinguish nightmare disorder from night terrors (which are episodes of panic and confusion, with difficulty waking or bringing to awareness, and of which the sufferer has no recollection). The ICD-11 definition of the diagnosis of a nightmare disorder is detailed below:

ICD-11 definition of the diagnosis of a nightmare disorder²

7B01.2 Nightmare disorder

How common is nightmare disorder? (Epidemiology)

Nightmares are common, particularly in children.

Children³

• 10-50% of those aged 3-6 years are estimated to suffer from nightmares that disturb their sleep, or that of their parents.

• They normally start between the ages of 2-5 years.

• A cross-sectional study of 4- to 12-year-olds suggests a peak prevalence between 7 and 9 years, with 87% and 95.7% of children retrospectively reporting bad dreams often or sometimes.⁴

Adults⁵

• A literature review reports that up to 85% of adults report at least one nightmare within the previous year, 8-29% report monthly nightmares and 2-6% report weekly nightmares.

• Older people were 20-50% less likely to have nightmares than young people.

Causes of nightmare disorder (aetiology)⁶

Several research groups have proposed that nightmare disorders result from increased hyperarousal and impaired fear extinction.

• Hyperarousal may develop during the day and be maintained at night. Hyperarousal is central to the pathophysiology of PTSD and insomnia.

• Normal sleep and dreaming may lead to fear extinction by recombining fear-inducing memories with novel and dissociated contexts. However, people with nightmare disorder continue to activate distressing and arousing memory fragments during sleep, reinforcing memories of fear. Individuals who have experienced stressful and negative-emotion-eliciting events may be particularly prone to this, as are those who have a tendency to react to stressors with distress and negative affect.

Factors hypothesised to lead to hyperarousal and impaired fear extinction include:

• Traumatic experiences and childhood adversity (disrupting emotional regulation).

• Differential susceptibility: some individuals are more sensitive to both positive and negative stimuli, leading to an increased likelihood of emotional and affective distress and nightmare disorder.

• The development of maladaptive beliefs, such as thought suppression (attempting to suppress unwanted thoughts and feelings), which increases the likelihood of those thoughts recurring in dreams.

• Sleep fragmentation due to obstructive sleep apnoea and other sleep-related hypoventilation syndromes.

• Medications that influence neurotransmitter activity and function.

Drugs linked to nightmares^{7 8}

• Antihypertensives:

  • Beta-blockers (the water-soluble beta-blockers such as atenolol are less likely to cause nightmares, as they are less likely to cross the blood-brain barrier).⁹

  • Centrally acting antihypertensives.

• Antidepressants: selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants and monoamine-oxidase inhibitors( MAOIs).

• Anti-Parkinsonian agents: levodopa, selegiline.

• Sedatives:

  • Ketamine¹⁰

  • Short-acting barbiturates

• Miscellaneous:

  • Rauwolfia alkaloids

  • Alpha-agonists

  • Flutamide

  • Procarbazine

• Medication withdrawal: benzodiazepine or alcohol withdrawal leads to a rebound of REM sleep which may increase nightmares.

It is theorised that recurrent nightmare elements may then become condensed into a 'nightmare script', where dream elements trigger the nightmare to occur. Nightmares may, therefore, persist long after the initial stressor has subsided.⁶

Symptoms of nightmare disorder (presentation) ³²

• Nightmares tend to start in the latter half of the sleep cycle, during REM sleep.

• The nightmare usually involves a threat of danger. This may be a physical threat such as being pursued, or a psychological one such as being teased. Frequent threatening characters for children are monsters, ferocious animals, ghosts, bullies or 'bad' people.

• It is unusual for the person to shout out, move or have autonomic disturbance during the experience, although these things may occur to a minor degree.

• When awoken it is usual for the person to be orientated, alert and responsive and to be receptive to calming by their parents/others. The details of the dream are usually remembered. This contrasts with night terrors where the person may be difficult to rouse and may not recall what has been troubling them.

• There may be a family history of similar problems.

Assessment

• Take a careful history, preferably also from parents, carers or relatives who have witnessed the event.

• Assess whether mental impairment, mental illness, depression, other central nervous system (CNS) disease or a febrile illness could be contributing.

• Consider medication history and alcohol/benzodiazepine withdrawal.

• Ask if there has been any recent traumatic event or conflict/stress.

Differential diagnosis

• Night terrors - the difference from nightmares is that: they tend to occur earlier rather than later during the night; the person may initially be unresponsive or disorientated; unlike nightmares, they usually cannot recall the event; signs of autonomic arousal such as dilated pupils, tachypnoea and tachycardia are more likely. See related separate article Night Terrors and Parasomnias.⁵

• Underlying organic brain disorder - eg, delirium or mental impairment.¹¹

• Post-traumatic stress disorder (PTSD): nightmares are a feature of PTSD. However, in PTSD the dream content often involves reliving the trauma and there are other symptoms such as poor sleep and daytime anxiety.¹²

• Medication or withdrawal from medication.¹³

• Recurrent febrile illness causing delirium or predisposing to nightmares (this may also cause night terrors).¹⁴

• Seizures.¹⁵

• Depressive illness with melancholic features may be associated in adults.¹⁶

• REM sleep behaviour disorder (a problem affecting particularly older adults).¹⁷

Investigations

Investigations are not usually necessary if the diagnosis is clear from the history. However, bear in mind that:

• Physical sleep disorders such as obstructive sleep apnoea and other types of sleep disordered breathing may coexist.¹⁸ If these problems are suspected, or the diagnosis is unclear, assessment at a sleep clinic may help.¹⁹

• If there is reason to suspect an underlying cause then electroencephalogram (EEG), blood tests and CNS imaging may be considered.

Management of nightmare disorder^{3 13}

• Reassurance of the patient or child and parents is all that is usually required.

• Helpful tips for children:
  

  • It may help to develop a relaxing bedtime routine that does not vary. Attention to causes of stress and upheaval within the home may help reduce the propensity to nightmares.

  • Use of night lights and other strategies that may reduce a child's anxiety levels at night can help.

  • If the nightmare is recurrent then it may help for the parents to talk through the nightmare and imagine a less scary ending.

• If the problem is occurring, say, on a more than twice-weekly basis persistently, then it may be worth referring for psychological or child-psychiatric input.

  • Cognitive behavioural therapy may be beneficial.

  • There is evidence that psychological techniques such as imaginal confrontation with nightmare contents or imagery re-scripting and rehearsal may be helpful.²⁰

• Drug treatment is not usually helpful and is more likely to cause nightmares. (This contrasts with some other types of sleep disorder, where medication may help.) However, in persistent cases, an REM-suppressant drug such as a tricyclic antidepressant may be helpful.

• Prazosin may be helpful for nightmares associated with PTSD,²¹ although there are reservations about conflicting data.⁶

Prognosis²²

In children, the prognosis is very good. The symptoms should resolve as time passes and after reassurance of the child and parents that this is a relatively normal experience for some young children. If the symptoms persist beyond the age of 6, consideration should be given to underlying conditions such as anxiety disorders, affective distress or PTSD.

In adults, untreated nightmare disorder may persist for decades.⁶